Impact of Mexico City on Regional Air Quality

Louisa Emmons

Jean-François Lamarque

NCAR/ACD

Chem-Climate WG White Paper

Hemispheric pollution to regional air quality: An issue of resolutionLouisa Emmons, Lyatt Jaegle, Loretta Mickley

Scientific advances to be accomplished within this project1) Improved understanding of feedbacks between climate change and air pollution: effects

of changing temperatures/precipitation/water vapor on chemistry, effects of changing emissions (biogenic NOx and VOC, lightning NOx, biomass burning, anthropogenic emissions), effects of changing meteorology (synoptic and hemispheric scales, stratosphere-troposphere exchange).

2) Improved understanding of feedbacks between climate change and export of pollution to the global atmosphere: will a warmer climate lead to more efficient export of pollution? How will it affect the long-range transport of pollution?

3) Improved understanding of the horizontal resolution needed to accurately predict the influences of future climate change on regional air quality and vice versa, through the use of the Weather Research and Forecasting (WRF) model in conjunction with CAM.

4) Exploration of the possibility of downscaling global simulations for analysis of regional air quality.

MILAGRO March 2006

Comprehensive set of measurements from city to regional scales

INTEX-B - NASA - DC-8 based in Houston

MIRAGE-Mex - NSF - C-130 based in Veracruz; ground measurements

MAX-Mex - DOE - G1

MCMA - Molina Center - surface and mobile lab

Model Simulations

Meteorology: NCEP/GFS analyses (42 levels)

Emissions: anthropogenic: POET-2000 and Mexico NEI (1999) biomass burning: GFED-2 and C. Wiedinmyer’s N.America

calculations (MODIS daily fire counts)

MOZART-4T42 (2.8°)T85 (1.4°)T170 (0.7°)

CAM-Chem0.47°x0.63°

Model EvaluationComparison to C-130 measurements - all flights binned by altitude

Finer resolution generally matches observations better

Mexico City points

Model Evaluation Comparison to surface measurements (T1)

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Ozone from Mexico City - March 2006

NO emissions from Mexico City are “tagged” to quantify O3 production

Average over March 2006, surface to 400 hPa

T85 has higher concentrations over Mexico City, but not larger regional impact

NO emissions

POET emissions inventory

March 19 strong outflow event

T85 - higher O3 throughout plume than T42

CAM-Chem - higher O3 over city but weaker plume

C-130 data will be used to evaluate2.8°

1.4° 0.5°

Radiative forcing of Mexico City emissions

CAM-Chem, 0.47x0.63 resolution, driven by NCEP-GFS winds

W/m2Shortwave flux at the surface 24-hour average

CAM-Chem/DART in support of ARCTAS

Arctic Research of the Composition of the Troposphere from Aircraft and Satellites (ARCTAS)

NASA aircraft campaign coincident with NOAA and DOE experimentsPart of POLARCAT/IPYApril - Fairbanks - Arctic haze, surface halogen chemistryJuly - near Edmonton - Boreal wildfires

Chemical ForecastsEnKF Data Assimilation: met

obs, MOPITT CO, MODIS AOD

Then free-running forecasts (5 days) for flight planning

Post-campaign AnalysisEvaluate and improve CAM-

ChemInterpret aircraft and satellite

observations